The Hammock
I built th Hammock for commuting because I make a 25 mile commute every
day (each way) and it was depressing to spend all that time in a car.
Since I couldn’t bike the whole 50 mile round trip every day I had to make
it compact enough to fit on the transit bus racks for part of the trip.
I hacked it from a 20-inch 5-speed Pacific “Hammer” model – a stingray
type. I thought the name was a good play on words. I would
much rather sit on a Hammock than a Hammer.
In addition to the 20-inch bike, I found an old SR 320 10-speed laying
in a neighbors yard crying out for a new life. The seat is from Vision
- a factory second that was purchased at last year’s factory tour.
The only fabrication I had to do was to braze nuts into the fork dropouts
(to anchor the drivetrain frame), braze ends to the seat stays on the drivetrain
frame and make a clamp for the steering tube to hold the drivetrain frametube.
Everything else is done with a drill, grinder or hacksaw. I am toying
with the idea of putting the rear drivetrain back on, adding a rear seat
and making it into a micro-tandem that I can ride with my youngest daughter,
but every time I say this to anyone they give me a very worried look.
In this view you can see where the donor frame was grafted to bolt to
the stingray. The top tube from the SR320 was taken to make the steertube.
It was grafted into the fork tube using a double-ended stem I made with
guidance from John Scoville. Right now it is too loose so I am trying
to get fork tube stock to get a better fit. It’s disconcerting to
have the steering slip when you ride.
Here you can see how I used a front fork for the seatback support.
It actually took me a while to find a fork and stem that would go together.
The stem had to have a detachable clamp so I could get it around the seatback
tube. At the bottom it is bolted into the hole made by the dropout
gusset. I plan to braze a bolt into this space to make it secure.
This is a closer view of the drive frame. I mounted it to be adjustable
because I may put a 16-inch fork on in the future to lower the seat.
The seat stay has a piece of tubing brazed on the end at 90 deg.to take
the fork bolt and pivots about this point. The stem sticking out
in front was just put in to keep rain out, but I may mount a fairing on
it eventually.
This is a closer view of the fork-bolt mount. Also clearly visible
is the drum brake. The front wheel has a home-made tandem hub made from
a couple of cheap steel press-flange hubs. Stopping power is quite
good, and I’ve had good reliability with these in the past. The rear
brake is the original cantilever. Shifting uses the original gears
and shifter from the stingray and the original front derailleur from the
SR320 with a cannibalized shift lever. The beauty of this design
is that the drivetrain comes jigged straight from the donor frame.
I didn't have to do any alignment.
Here is a closer look at the steering tube clamp. It was made
by brazing a couple of pieces of plate to a piece of tube and then slicing
the tube between the plates. One bolt clamps it tight around the
steering tube and the other holds the front frame tube. The coiled
wire is from my battery light.
Remaining work to be done includes installing fenders, improving the
seat-base clamp (which slips alot now) and replacing the steering tube
and brazing in the seatback support bolt. Meanwhile I’ve been commuting
to work on it for a few weeks now, riding about 7 miles to catch the bus
and then putting it on the bus rack for most of the rest of the ride (I
also have to ride the bike the last 2 miles from the last bus stop).
I would like to put a front fairing on it too, but then I’m anxious to
get started on a fully-faired commuting streamliner so I can ride the 50-mile
round trip to work every day.
DISCLAIMER: If you build a bike like this for yourself, be aware
that riding with front wheel drive is like learning to ride all over again.
You’ll be wobbly for the first few months that you ride so don’t go out
in traffic on it until you are confident of your maneuvering ability.